I've been making sourdough bread regularly for a while.  I am in love with this bread!

First, you must have your sourdough starter.   Instructions can be found here.

The night before you want bread:

- bring starter to room temperature

- measure 1 cup starter

- in large bowl, mix starter with 1-1/2 cups lukewarm water, then stir in 2-1/2 cups bread flour.

- mix well, cover, and let sit out overnight

The next morning:

- your mixture should be all bubbly

- mix in: 3 T sugar, 1 t. salt and 3 T olive oil

- add 3 to 3-1/2 cups bread flour, mixing in as much as you can with a spoon and then kneading the rest in

- knead on a floured surface until you have a smooth, elastic dough

- put into greased bowl, cover and set in warm place to  rise

When it has doubled, punch it down.  Put the dough on a floured surface and divide into two parts. Cover these two lumps for about 10 minutes and let them rest. Make them into two round loaves. Put the two loaves on a greased baking sheet, and cover again to let them rise until they are about double in size (about 30 minutes). Then it's time to bake the loaves, in a 375-degree oven for about 30 to 35 minutes.

I always  take a sharp knife and cut a criss cross pattern into the top of the loaves before putting them into the oven.  When they come out, I brush butter onto the hot loaves.

Allow them to cool, slice, and enjoy.  This is great bread with a spaghetti dinner, and it makes wonderful French toast for breakfast.